The building of decks, sheds, etc. by the average homeowner or in a commercial construction applications such as bridge work, parking garages, and all industrial construction as well, columns made of poured concrete both above and below grade are typically aligned using plumb lines and supported with braces. Modern construction codes also may require a concrete footing at the required depth below the frost line to support the legs or base of the structure. Typically forms were set up with plumb lines and dug then braced to the ground and backfilled based upon the measurements of the lines. However, plumb lines can easily move or be repositioned because the lines may collapse or move when not under tension and therefore may shift or worse the top may tilt and while the base is properly positioned the top of the concrete column is incorrectly positioned to receive the leg of the structure. In extreme cases the cured column needs to be excavated and re-poured or in certain areas incorrect positioning has required larger sized columns than required just for top alignment purposes.